netfilter: nf_conntrack: fix warning and prototype mismatch

net/netfilter/nf_conntrack_core.c:46:1: warning: symbol 'nfnetlink_parse_nat_setup_hook' was not declared. Should it be static?

Including the proper header also revealed an incorrect prototype.
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/nf_conntrack_core.c

@@ -39,11 +39,11 @@
 #include <net/netfilter/nf_conntrack_extend.h>
 #include <net/netfilter/nf_conntrack_acct.h>
 #include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
 
 #define NF_CONNTRACK_VERSION	"0.5.0"
 
-unsigned int
-(*nfnetlink_parse_nat_setup_hook)(struct nf_conn *ct,
+int (*nfnetlink_parse_nat_setup_hook)(struct nf_conn *ct,
 				      enum nf_nat_manip_type manip,
 				      struct nlattr *attr) __read_mostly;
 EXPORT_SYMBOL_GPL(nfnetlink_parse_nat_setup_hook);